As a conventional technology for converting 16-bits and 10-bits, there has been known Patent Literature 1. When the conventional technology is applied to a burst access of SDRAM, a cell of 12-pixels (e.g., 3×4) is obtained from one burst access. In order to dispose cells such that they fill an image block of 8×8 pixels which is a unit in image processing and is frequently used in image compression, 6-cells are required. In this case, data of 8-pixels is not used in the image processing of the block of 8×8 pixels to be wasted. This decreases access efficiency. In the case of this example, since it accesses 72-pixels for 64-pixels, access efficiency is about 89%. Further, if one pixel has 10-bits, since it accesses 128-bits for access of 12 pixels (=120-bits), access efficiency is about 94%. Nearly, access efficiency becomes about 88%.
The access efficiency of 89% is inadequate, and it is desirable that the access efficiency becomes closer to 100% by improving it to the extent possible.